The present invention relates to an improved fan construction which facilitates access to the fan parts for repair or cleaning.
Early, heavy duty industrial fans were typically constructed with the fan and motor assemblies permanently affixed to the fan housing. When cleaning or repair was required, the fan unit was disassembled or access to the fan interior was provided through an access door. Either procedure requires excessive amounts of time. Further, access to all of the parts was often difficult.
An early example of an attempt to overcome the above deficiencies is disclosed in British Patent No. 407,268 which issued to John Marshall, a British subject. The Marshall fan is an axial flow fan employing a propellor to induce the air flow. The fan assembly and motor are carried by an access door which exposes them on opening of the door for cleaning or repair. Inlet fairings for the fan are supported within the housing and are stationary during opening and closing of the door.
A later industrial fan is illustrated in U.S. Pat. No. 3,871,795 issued Mar. 18, 1975, for FAN CONSTRUCTION in the name of Robert T. Habdo et al. The Habdo fan is a centrifugal type which, in its axial flow embodiment, has the fan assembly and motor mounted on the door with the motor being carried by the door outside of the flow path. As is well known in the art, such fans require an inlet funnel for efficient operation, the inlet funnel and fan wheel inlet being overlapped during normal operation. The Habdo funnel is secured within the fan housing requiring that the fan assembly be lifted to provide a clearance between the fan inlet and inlet funnel when the door is opened. This lifting operation is cumbersome and requires a step that may be forgotten prior to door opening to result in damage to the inlet funnel, the fan wheel or both.
Another system which provides an overlap between the fan wheel inlet and the inlet funnel is disclosed in U.S. Pat. No. 4,253,796 issued Mar. 3, 1981, for Fan or Blower Assembly in the name of Philipps et al. The Philipps construction provides an adjustable inlet funnel such that the inlet funnel can be positioned relative to the fan wheel inlet without an overlap. This eliminates the need to lift the fan assembly and the door on door opening. However, failure to properly position the inlet funnel relative to the fan inlet prior to door opening can again result in damage to the inlet funnel, fan wheel or both.